inject a tenant ID into MongoDB

envoy_config.yaml

static_resources:
  listeners:
  - name: listener_0
    address:
      socket_address:
        address: 0.0.0.0
        port_value: 27017
    filter_chains:
    - filters:
      - name: envoy.filters.network.mongo_proxy
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.filters.network.mongo_proxy.v3.MongoProxy
          stat_prefix: mongo
          access_log:
          - name: envoy.access_loggers.file
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.access_loggers.file.v3.FileAccessLog
              path: /dev/stdout
          generate_id: true
          emit_dynamic_metadata: true
          decorate_all_responses: true
          http_filters:
            - name: envoy.filters.http.lua
              typed_config:
                "@type": type.googleapis.com/envoy.extensions.filters.http.lua.v3.Lua
                inline_code: |
                  function envoy_on_request(request_handle)
                    local headers = request_handle:headers()
                    local tenant_id = headers:get("x-tenant-id")
                    if tenant_id ~= nil then
                      local query = request_handle:body():asBytes()
                      local new_query = string.gsub(query, '{"%$query":', '{"%$query": {"tenant_id": "' .. tenant_id .. '"},')
                      request_handle:logInfo("Rewrote query to: " .. new_query)
                      request_handle:body():setBytes(new_query)
                    end
                  end
      - name: envoy.filters.network.tcp_proxy
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.filters.network.tcp_proxy.v3.TcpProxy
          stat_prefix: tcp
          cluster: mongo
          access_log:
          - name: envoy.access_loggers.file
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.access_loggers.file.v3.FileAccessLog
              path: /dev/stdout
  clusters:
  - name: mongo
    connect_timeout: 0.25s
    type: logical_dns
    dns_lookup_family: V4_ONLY
    lb_policy: round_robin
    load_assignment:
      cluster_name: mongo
      endpoints:
      - lb_endpoints:
        - endpoint:
            address:
              socket_address:
                address: mongo-service
                port_value: 27017